Measuring the magnetic field strength in L1498 with Zeeman-splitting observations of CCS

We have measured the Zeeman splitting of the CCS J(N) = 3(2)-2(1) line at 3 3 GHz toward L1498, a dense preprotostellar core, in an effort to measure t he line-of-sight component of its magnetic field. With approximately 35 hr of data on source (70 hr total) in good weather, the data suggest a line-of -sight component of the magnetic field in L1498 of 48 +/- 31 muG, yielding an upper limit of B-los < 100 <mu>G at the 95% confidence level. This upper limit provides some constraints on models. Our results show that the techn ique we have adopted to measure CCS Zeeman splitting holds great promise fo r determining magnetic field strengths in cloud cores using lower-frequency transitions, in particular the CCS J(N) = 1(0)-0(0) line at 11 GHz. At thi s transition, the frequency splitting per gauss is 3 times that at 33 GHz, the brightness temperature is comparable to the line, and receiver systems can be made more sensitive.